This on-going research attempts to refine the assessment of coronary prone behavior, especially the Type A behavior pattern. (TABP). Previous studies in the literature suggested that the global TABP was an independent risk factor for coronary heart disease, but more recent studies did not replicate these findings. When specific components of Type A were examined in the Multiple Risk Factor Intervention Trial (MRFIT), only hostility ratings predicted CHD (RR = 1.69, p < .05, n = 576). In an attempt to improve interview-derived assessments of hostility, more reliable and valid ratings of hostility were developed based on the five factor model of personality and its conceptualization of hostility. The present research examines these new ratings as predictors of CHD morbidity and mortality.